Dear kate:
I wouldn’t feel pressured, if I was you, to get pregnant because your three year old asked you to “grow him a little sister”- as cute as it is that he asked for that. Maybe he saw a baby girl in the park or in preschool and he feels like having one of those in his home, similar to wanting a toy. It doesn’t mean he knows what he asked for, that he is aware of what it means to have a younger sibling (at least 4 years younger than him).
How long has it been possible for you to get pregnant (not on birth control) and yet, you didn’t?
anita